Process for dyeing a textile substrate containing residual oligomers

ABSTRACT

A process for dyeing a textile substrate containing residual oligomers includes the steps of:
         a) attaching the textile substrate on a mounting carrier to constitute a substrate-loaded carrier which is to be subjected to supercritical dyeing in a dyeing autoclave; and   b) overlying the textile substrate with a micro-porous film which includes pores having a pore size such that when the textile substrate is dyed in the dyeing autoclave, a dye-containing supercritical fluid is allowed to pass through the micro-porous film to permit the textile substrate to be dyed while the residual oligomers entrained in the supercritical fluid are retained by the micro-porous film.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 107121281, filed on Jun. 21, 2018.

FIELD

The disclosure relates to a process for dyeing a textile substrate, and more particularly to a process for dyeing a textile substrate containing residual oligomers.

BACKGROUND

A traditional water-based dyeing process is usually followed by a water washing process, resulting in undesirable production of a large amount of waste water. Therefore, the water-based dyeing process is being replaced with a supercritical fluid dyeing process to alleviate the problem of discharging the waste water. However, the processes of synthesizing polymer such as polyester and spinning yarns from polymeric fibers may produce a small amount of residual oligomers, which may leach from a textile made from the yarns due to flowing of the supercritical fluid through the textile in a high temperature dye bath, resulting in formation of color stain on the textile after the supercritical fluid dyeing process. In addition, the residual oligomers may aggregate with the dye that is contained in the supercritical fluid to form sediments that may be deposited on an inner wall of a dyeing autoclave, resulting in pollution thereof.

Currently, there is still a need to conduct a water washing process after the supercritical fluid dyeing process to remove the residual oligomers from the dyed textile. Therefore, the problem of discharging waste water cannot be effectively alleviated. In addition, only about 15% to 25% of the residual oligomers may be removed by the water washing process.

SUMMARY

Therefore, an object of the disclosure is to provide a process for dyeing a textile substrate containing residual oligomers which can overcome the aforesaid shortcomings of the prior art.

According to the disclosure, there is provided a process for dyeing a textile substrate containing residual oligomers, comprising the steps of:

a) attaching the textile substrate on a mounting carrier to constitute a substrate-loaded carrier which is to be subjected to supercritical dyeing in a dyeing autoclave; and

b) overlying the textile substrate of the substrate-loaded carrier with a micro-porous film which includes pores having a pore size such that when the textile substrate is dyed in the dyeing autoclave, a dye-containing supercritical fluid is allowed to pass through the micro-porous film to permit the textile substrate to be dyed while the residual oligomers entrained in the supercritical fluid are retained by the micro-porous film.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiment(s) with reference to the accompanying drawings, of which:

FIG. 1 is a scanning electron microscopy image of a treated polyester textile of Example 1;

FIG. 2 is a scanning electron microscopy image of a treated polyester textile of Comparative Example 1; and

FIG. 3 is a scanning electron microscopy image of a treated polyester textile of Comparative Example 2.

DETAILED DESCRIPTION

A process for dyeing a textile substrate containing residual oligomers according to the disclosure comprises the steps of:

a) attaching the textile substrate on a mounting carrier to constitute a substrate-loaded carrier which is to be subjected to supercritical dyeing in a dyeing autoclave; and

b) overlying the textile substrate of the substrate-loaded carrier with a micro-porous film which includes pores having a pore size such that when the textile substrate is dyed in the dyeing autoclave, a dye-containing supercritical fluid is allowed to pass through the micro-porous film to permit the textile substrate to be dyed while the residual oligomers entrained in the supercritical fluid are retained by the micro-porous film.

In certain embodiments, the pore size of the pores of the micro-porous film is smaller than a particle size of the residual oligomers. In certain embodiments, the pore size of the pores of the micro-porous film is in a range from 0.1 μm to 1.0 μm. In certain embodiments, the pore size of the pores of the micro-porous film is in a range from 0.2 μm to 0.8 μm.

In certain embodiments, the micro-porous film has a thickness in a range from 10 mm to 90 mm.

In certain embodiments, the micro-porous film is made from a polymeric material. In certain embodiments, the polymeric material for making the micro-porous film is polytetrafluoroethylene. In certain embodiments, the polymeric material for making the micro-porous film is polyurethane. In certain embodiments, the polymeric material for making the micro-porous film is polypropylene.

In certain embodiments, the textile substrate is made from a polyester material.

In certain embodiments, the dye-containing supercritical fluid includes a disperse dye. The disperse dye used in the following examples includes Disperse Red 92 and Disperse Blue 60.

In certain embodiments, in step a), the mounting carrier is tubular-shaped, and the textile substrate is wound on the tubular-shaped mounting carrier around an axis.

In certain embodiments, the dye-containing supercritical fluid includes supercritical carbon dioxide.

Examples of the disclosure will be described hereinafter. It is to be understood that these examples are exemplary and explanatory and should not be construed as a limitation to the disclosure.

Example 1

A polyester textile (10 g; commercially available from Far Eastern New Century Corporation, Taiwan; Catalogue Number: 75/72 SDR) was wound on a stainless steel, tubular-shaped mounting carrier around an axis.

A micro-porous film of polytetrafluoroethylene (ePTFE; commercially available from Yeu Ming Tai Chemical Industrial Co., Ltd., Taiwan; Catalogue Number: STF-5126; size: 15 cm×15 cm; thickness: 35 mm; pore size: 0.2-0.8 μm) was tightly and fully overlaid on the polyester textile that was wound on the stainless steel, tubular-shaped mounting carrier in a manner that the polyester textile was not exposed from the micro-porous film. The micro-porous film was then fixed by cotton or nylon thread.

The stainless steel, tubular-shaped mounting carrier together with the polyester textile and the micro-porous film was placed in an autoclave (1 L). Liquefied carbon dioxide (150±3 g) was introduced into the autoclave and was heated under turbulence to a temperature ranging from 120° C. to 130° C. The autoclave was pressurized with carbon dioxide gas to a pressure ranging from 250 bar to 300 bar to form supercritical carbon dioxide in the autoclave for a period of 120 min.

Afterwards, the temperature and the pressure of the autoclave were reduced to 60° C. and a normal pressure, respectively. Following treatment of the supercritical carbon dioxide, the polyester textile (referred below as a supercritical carbon dioxide-treated polyester textile) was detached from the stainless steel, tubular-shaped mounting carrier.

Example 2

The procedures of Example 2 were similar to those of Example 1 except that the micro-porous film of ePTFE was replaced with a micro-porous film of polypropylene (PP; commercially available from Finetech Research and Innovation Corporation, Taiwan; Catalogue Number: M-PP047N0451; size: 15 cm×15 cm; thickness: 47 mm; pore size: 0.45 μm).

Example 3

The procedures of Example 3 were similar to those of Example 1 except that the micro-porous film of ePTFE was replaced with a micro-porous film of polyurethane (PU; commercially available from Taiwan GUL Co. Ltd.; Catalogue Number: ITPUC035137; size: 15 cm×15 cm; thickness: 35 mm; pore size: 0.2-0.6 μm).

Example 4

The procedures of Example 4 were similar to those of Example 1 except that Disperse Red 92 (0.05 g) was placed into the autoclave prior to the introduction of liquefied carbon dioxide into the autoclave.

Example 5

The procedures of Example 5 were similar to those of Example 1 except that Disperse Blue 60 (0.05 g) was placed into the autoclave prior to the introduction of liquefied carbon dioxide into the autoclave.

Comparative Example 1

The procedures of Comparative Example 1 were similar to those of Example 1 except that the polyester textile wound on the stainless steel, tubular-shaped mounting carrier was not overlaid with the micro-porous film of ePTFE.

Comparative Example 2

The procedures of Comparative Example 2 were similar to those of Example 4 except that the polyester textile wound on the stainless steel, tubular-shaped mounting carrier was not overlaid with the micro-porous film of ePTFE.

Comparative Example 3

The procedures of Comparative Example 3 were similar to those of Example 5 except that the polyester textile wound on the stainless steel tubular-shaped mounting carrier was not overlaid with the micro-porous film of ePTFE.

Scanning Electron Microscopic Observation:

Each of the supercritical carbon dioxide-treated polyester textiles of Example 1, and Comparative Examples 1 and 2 was observed at a surface thereof which was distal from the stainless steel, tubular-shaped mounting carrier during the treatment of supercritical carbon dioxide using a scanning electron microscope. The results for the supercritical carbon dioxide-treated polyester textiles of Example 1, and Comparative Examples 1 and 2 are shown in FIGS. 1 to 3, respectively.

As shown in FIG. 1, the observed surface of the supercritical carbon dioxide-treated polyester textile of Example 1 is smooth and even. In contrast thereto, as shown respectively in FIGS. 2 and 3, the observed surfaces of the supercritical carbon dioxide-treated polyester textiles of Comparative Examples 1 and 2 have a significant amount of residual oligomer particles, which are indicated by arrows. It is thus demonstrated that as compared to the treatments of the polyester textile of Comparative Examples 1 and 2, the treatment of the polyester textile of Example 1 significantly decreased the amount of residual oligomer particles that remained thereon.

Quantitative Analysis of Residual Oligomers:

50 mg of each of the supercritical carbon dioxide-treated polyester textiles of Examples 1 to 5 and Comparative Examples 1 to 3, and 50 mg of each of the treated micro-porous films of Examples 1 to 4 were placed respectively in a container, following by addition of 1.5 ml of a solvent mixture of hexafluoroisopropanol and chloroform in a volume ratio of 3:2 and left to stand overnight. Then, chloroform (10 ml) and methanol (5 ml) were added into the container, followed by centrifugation and filtration to obtain a filtrate. A determined amount of the filtrate was taken for a quantitative analysis of residual oligomers using high performance liquid chromatography (HPLC) (mobile phase: a solvent mixture of methanol and acetonitrile; column: a C18 HPLC column commercially available from ES Industries; fillers: particle size of 3.5 μm, pore size of 100 Å, specific surface area of 350 m²/g; elution temperature: 35° C.). Retention rate of each of the micro-porous films of Examples 1 to 5 was calculated according to Formula (1). The results are shown in Table 1.

Retention rate=[A1/(A1+A2)]×100%  (1)

wherein

A1 is an amount of residual oligomers remaining on a micro-porous film, and

A2 is an amount of residual oligomers remaining on a polyester textile.

TABLE 1 A2 ((Amount of A1 (Amount of residual oligomers residual oligomers remaining on a remaining on a Retention polyester textile) micro-porous film) rate Ex. 1 5250 ppm 4550 ppm 46.4% Ex. 2 7090 ppm 2870 ppm 28.8% Ex. 3 7950 ppm 1980 ppm 19.9% Ex. 4 5760 ppm 4180 ppm 42.1% Ex. 5 5230 ppm 4570 ppm 46.6% Comp. Ex. 1 10060 ppm — — Comp. Ex. 2 12090 ppm — — Comp. Ex. 3 11758 ppm — —

As shown in Table 1, the total amounts of the residual oligomers (i.e., A1+A2) of Examples 1 to 5 and Comparative Examples 1 to 3 are all about 10000 ppm. The retention rates achieved by the micro-porous films of Examples 1 to 5 are in a range from 19.9% to 46.6%. Specifically, the retention rates achieved by the ePTFE micro-porous films of Examples 1, 4, and 5 are all above 40%. It is thus demonstrated that in Examples 1 to 5, a significant amount of the residual oligomers remaining on the polyester textile can be transferred to and retained by the micro-porous film, so as to significantly reduce the amount of the residual oligomers remaining on the polyester textile. Therefore, the currently required water washing process that is conducted after the supercritical fluid dyeing process can be omitted in the process for dyeing a textile substrate containing residual oligomers according to the disclosure.

Color Measurement:

CIE L*,a*,b* color values of each of the supercritical carbon dioxide-treated polyester textiles of Examples 4 and 5 and Comparative Examples 2 and 3 were measured using a color difference meter (Manufacturer: Nippon Denshoku Co., Ltd; Model: NE 4000). The results are shown in Table 2.

TABLE 2 CIE L* value CIE a* value CIE b* value Ex. 4 9.88 10.58 3.84 Comp. Ex. 2 28.58 2.71 1.28 Ex. 5 10.12 3.32 −9.89 Comp. Ex. 3 27.32 1.48 −2.33

As shown in Table 2, the CIE L* value of each of the supercritical carbon dioxide-treated polyester textiles of Examples 4 and 5 is much smaller than that of each of the supercritical carbon dioxide-treated polyester textiles of Comparative Examples 2 and 3. It is thus demonstrated that a dyeing degree (i.e., a coloring power) of each of the supercritical carbon dioxide-treated polyester textiles of Examples 4 and 5 is much higher than that of each of the supercritical carbon dioxide-treated polyester textiles of Comparative Examples 2 and 3.

The CIE a* value of the supercritical carbon dioxide-treated polyester textile of Example 4 is much larger than that of the supercritical carbon dioxide-treated polyester textile of Comparative Example 2. It is thus demonstrated that a dyeing degree of a red dye (i.e., Disperse Red 92) of the supercritical carbon dioxide-treated polyester textile of Example 4 is much higher than that of the supercritical carbon dioxide-treated polyester textile of Comparative Example 2, so that the supercritical carbon dioxide-treated polyester textile of Example 4 is relatively red compared to the supercritical carbon dioxide-treated polyester textile of Comparative Example 2.

The CIE b⁺ value of the supercritical carbon dioxide-treated polyester textile of Example 5 is much smaller than that of the supercritical carbon dioxide-treated polyester textile of Comparative Example 3. It is thus demonstrated that a dyeing degree of a blue dye (i.e., Disperse Blue 60) of the supercritical carbon dioxide-treated polyester textile of Example 5 is much higher than that of the supercritical carbon dioxide-treated polyester textile of Comparative Example 3, so that the supercritical carbon dioxide-treated polyester textile of Example 5 is relatively blue compared to the supercritical carbon dioxide-treated polyester textile of Comparative Example 3.

In view of the aforesaid, the process for dyeing a textile substrate containing residual oligomers according to the disclosure can effectively reduce the amount of the residual oligomers remaining on the polyester textile after supercritical dyeing treatment, so that the currently required water washing process that is conducted after the supercritical fluid dyeing process can be omitted. In addition, the process for dyeing a textile substrate containing residual oligomers according to the disclosure enhances the dying degree of the supercritical carbon dioxide-treated polyester textile.

In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment(s). It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects, and that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure.

While the disclosure has been described in connection with what is (are) considered the exemplary embodiment(s), it is understood that this disclosure is not limited to the disclosed embodiment(s) but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

What is claimed is:
 1. A process for dyeing a textile substrate containing residual oligomers, comprising the steps of: a) attaching the textile substrate on a mounting carrier to constitute a substrate-loaded carrier which is to be subjected to supercritical dyeing in a dyeing autoclave; and b) overlying the textile substrate of the substrate-loaded carrier with a micro-porous film which includes pores having a pore size such that when the textile substrate is dyed in the dyeing autoclave, a dye-containing supercritical fluid is allowed to pass through the micro-porous film to permit the textile substrate to be dyed while the residual oligomers entrained in the supercritical fluid are retained by the micro-porous film.
 2. The process according to claim 1, wherein the pore size of the pores of the micro-porous film is smaller than a particle size of the residual oligomers.
 3. The process according to claim 2, wherein the pore size of the pores of the micro-porous film is in a range from 0.1 μm to 1.0 μm.
 4. The process according to claim 3, wherein the pore size of the pores of the micro-porous film is in a range from 0.2 μm to 0.8 μm.
 5. The process according to claim 1, wherein the micro-porous film has a thickness in a range from 10 mm to 90 mm.
 6. The process according to claim 1, wherein the micro-porous film is made from a polymeric material.
 7. The process according to claim 6, wherein the polymeric material is polytetrafluoroethylene.
 8. The process according to claim 6, wherein the polymeric material is polyurethane.
 9. The process according to claim 6, wherein the polymeric material is polypropylene.
 10. The process according to claim 1, wherein the textile substrate is made from a polyester material.
 11. The process according to claim 1, wherein the dye-containing supercritical fluid includes a disperse dye.
 12. The process according to claim 1, wherein in step a), the mounting carrier is tubular-shaped, and the textile substrate is wound on the tubular-shaped mounting carrier around an axis.
 13. The process according to claim 1, wherein the dye-containing supercritical fluid includes supercritical carbon dioxide. 